Rapid and precise characterization of sub-µm surface defects using laser scatterometer devising a polygonal-shaped waveguide with double-slit aperture

We present a method of various defects detection on a flat surface using a polygonal-shaped waveguide devised laser scatterometer capable of providing sub-µm precision. The optimized polygonal shape of the waveguide with double-slit aperture substantially improves the detection efficiency of scattered beam more than 10 times compared to that of the conventional circular-shaped waveguide. The scatterometer enables quantification of sub-µm lateral size and height of defects by counting the number of pixels and peak intensity, respectively. We validated the performance of the proposed inspection system by measuring a standard defective specimen and successfully apply to a pilot production line for inspection of 250×140 mm² size glass panels providing 31,250 × 16,000 spatial resolution with the capability of a measuring time less than 10 s.